Electrochemical behaviour of dimethyl hydrazones - part – 1 cyclohexanone dimethyl hydrazone

The polarographic behaviour of cyclohexanone dimethyl hydrazone at dropping mercury electrode in aqueous alcoholic medium has been investigated in presence of 0.1 M KC1 as supportingelectrolyle.The effect of depolariser concentration, pH, and drop time on the wave characteristics and the reaction mechanism occurring at the surface of the mercury drop electrode have been studied. Well defined ineversible diffusion controlled two cathodic waves were obtained in this medium between the DH ranae 6 and 8.2 and a single wave of irreversible and diffusion controlled nature was obtained between the pH12 to 6 and 8.210 10.4. a, n. and 'n' values and electrochemical reaction order of the system were calculated. The linearity of the diffu%on current with concentration of the depolariser provides a rapid and precise method for the estimation of this dimethyl hydrazone in the concentration down to 10-4 M in aqueous alcoholic medium

Time-resolved optically stimulated luminescence and spectral emission features of α-Al2O3:C

The authors acknowledge financial support from Rhodes University and the National Research Foundation of South Africa (Grant UID 87358).Abstract This report is concerned with the influence of measurement temperature on luminescence lifetime and on the spectral emission features of luminescence from α-Al2O3:C. The lifetimes were determined from time-resolved luminescence spectra. Spectral measurements were done using thermoluminescence and X-ray excited optical luminescence. The emission spectra of α-Al2O3:C studied in this work shows prominent bands at 330, 380 and 420 nm associated with vacancies in the oxygen sub-lattice in α-Al2O3:C and an additional band at 695 nm due to Cr substitution for Al. Emission bands below 500 nm are independent of temperature below 125 °C but widen with temperature. Direct evidence of thermal quenching of the 420 nm emission band is provided. Beyond 200 °C, the 380 and 420 nm bands merge and widen, with the 420 nm emission dominant. Before the onset of thermal quenching, luminescence lifetimes are affected by retrapping both in the shallow- and in the main electron trap. This was deduced from features of time-resolved luminescence spectra measured from samples with and without the shallow trap. Additional measurements with temperature decreasing from 160 to 20 °C, after phototransfer as well as after a considerable delay between irradiation and measurement, suggest that the change in lifetimes could also be related to other factors including slight shifts in emission wavelength for the 380 and 420 nm emissions.PostprintPeer reviewe

Evaluation of CSM-CERES-wheat in simulating wheat yield and its attributes with different sowing environments in Tarai region of Uttarakhand

Crop Environment Resource Synthesis (CSM-CERES)-Wheat model was used to simulate responses of two wheat varieties with various sowing environments. In this context, during the year 2007-08 and 2008-09, experiments on three sowing dates viz. November 20, December 15, and January 9 and two varieties (PBW-343 and WH-542) with three replications were conducted at the Norman E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture & Technology, Pantnagar (29°N, 79.29°E with 243.80 m above msl). Soil, plant, management and climatic data were collected from the experimental field. The data of 2007-08 and 2008-09 were used for model calibration and validation, respectively. Results revealed that the for model outputs were in good agreement with their corresponding observed values with 20th November sown crop than other sowings of crop in terms of phenological events, biomass accumulation and grain yields. However, variety PBW-343 showed close proximity between simulated and observed outcomes with all sowing dates. The percent root mean square error (% RMSE) values ranged from 5.9 – 15.6%, 2.2 – 7.6% for days to attain anthesis and physiological maturity, respectively. Moreover, %RMSE and t-value ranged from 5.7–12.2% (t= -4.5 to 1.8), 1.6 – 3.3% (t= -4.1 to 4.5) and 1.9 – 5.8% (t= -3.7 to 1.5) for product weight, vegetative weight and product harvest index, respectively. Inspite of that, model fails to simulate maximum leaf area index having % RMSE from 53.2 – 62.9%. These results indicate that CERES-Wheat model can be used as a tool to support decision-making for wheat production in Tarai region of Uttarakhand

Deposition of zinc on molten lead by electrochemical tecgniques in molten LiCl-KCl

The electrochemical incorporation of Zn onto molten Pb working electrode from molten eutectic of LiCl and KC1 containing 0.0179, 0.0313 and 0.0477 mol ZnC12 at 673K was investigated by cyclic voltammetry at different scanning rates and by chronocoulometry. The results show that the initial formation of lead-zinc solid solution is followed by the formation of Pb-Zn intermetallic compoun

Time-resolved optically stimulated luminescence and spectral emission features of α-Al₂O₃:C

Abstract This report is concerned with the influence of measurement temperature on luminescence lifetime and on the spectral emission features of luminescence from α-Al2O3:C. The lifetimes were determined from time-resolved luminescence spectra. Spectral measurements were done using thermoluminescence and X-ray excited optical luminescence. The emission spectra of α-Al2O3:C studied in this work shows prominent bands at 330, 380 and 420 nm associated with vacancies in the oxygen sub-lattice in α-Al2O3:C and an additional band at 695 nm due to Cr substitution for Al. Emission bands below 500 nm are independent of temperature below 125 °C but widen with temperature. Direct evidence of thermal quenching of the 420 nm emission band is provided. Beyond 200 °C, the 380 and 420 nm bands merge and widen, with the 420 nm emission dominant. Before the onset of thermal quenching, luminescence lifetimes are affected by retrapping both in the shallow- and in the main electron trap. This was deduced from features of time-resolved luminescence spectra measured from samples with and without the shallow trap. Additional measurements with temperature decreasing from 160 to 20 °C, after phototransfer as well as after a considerable delay between irradiation and measurement, suggest that the change in lifetimes could also be related to other factors including slight shifts in emission wavelength for the 380 and 420 nm emissions.</p